Various motors are basically identical in structure with a stator and a rotor. However, motors are classified according to a rotating principle of the rotator by mutual interaction between the stator and the rotor. Further, motors are classified according to kinds of power supplied to the stator coil, a phase or a method of winding the stator coil.
First, a conventional motor will be described referring to FIG. 1 and FIG. 2.
As illustrated in FIG. 1, a stator 1 includes: a stator core 2; teeth 3 formed plural along a circumference of the stator core 2; and an upper insulator 4 and a lower insulator 5 that respectively inserted into upper and lower portions of the stator core 2 and the teeth 3 to be wound with stator coil 6.
Moreover, a rotator (unshown) being connected to a rotating shaft (unshown) is disposed inside the stator 1, and a printed circuit board (PCB) 60 is fixed at an upper portion of the stator 1. That is, a fixed protrusion 22 formed at an upper portion of the stator 1 is inserted to a hole 61 formed in the PCB 60 to fix the PCB 60.
The stator 1, the rotor and the PCB 60 are accommodated inside a bracket 70. Meanwhile, the rotating shaft and the rotator to be rotated are supported by bearings (unshown) fixed at the bracket 70.
There are nine teeth 3 formed in FIG. 1 and FIG. 2 illustrating a winding of a stator coil 6 to each of the teeth 3 in concentrated winding type. FIG. 2 is an unfolded view of an outer circumference surface of the stator 1 illustrated in FIG. 1. Three phases (u, v, and w) of power are supplied to the illustrated stator coils 6 of each phase wound in 120° interval. A method for winding conventional stator coil 6 in such type of stator 1 is described as follows.
First, a stator coil of u phase 7 is wound at teeth No. 1 in clockwise direction (arrow direction). A direction of winding does not have to be a clockwise direction. However, in any case, the stator coils of each phase only have to be wound in identical direction.
After completing the winding, a connection line 12 of the stator coil of u phase 7 is escaped outside of the insulator through a groove 10 formed in the insulator 4. One end of the connection line is fixed at a protrusion 11 that determines a position of the connection line and is extended along an outer circumferential surface of the insulator. The extended connection line 12 is inserted again inside the insulator through a groove 10 formed in the insulator and wound again at teeth No. 4 in clockwise direction. In the same way, the connection line 12 is positioned to be wound again at teeth 7 in clockwise direction and a terminal end of the stator coil forms a neutral point (N).
Here, the stator coil of u phase 7 has two connection lines 12. The two connection lines 12 are positioned to be at different heights from each other. An adjustment of such positions are accomplished by the protrusion 11 formed at various heights.
A stator coil of v phase 8 is wound at teeth No. 2, teeth No. 5 and teeth No. 8. A stator coil of w phase 9 is wound at teeth No. 3, teeth No. 6 and teeth No. 9. Here, the stator coil of v phase 8 has two connection lines 13 and the stator coil of w phase 9 has two connection lines 14. These connection lines are positioned at heights different from each other.
Here, starting ends of the stator coils of u, v, and w phases are connected to their corresponding power supplies and the terminal ends of each stator coils are connected to each other to form the neutral point (N).
Meanwhile, as shown in FIG. 2, the connection lines 12, 13, and 14 of the stator coils of u, v, and w phases have to be positioned to secure insulating distances from each other. Accordingly, such connection lines have to be positioned to have heights different from each other. For this, the protrusions 11 have to be formed at heights different from each other along the outer circumferential surface of the insulator 4.
Moreover, since such connection lines are positioned only at the upper insulator 4, the heights where the protrusions 11 are formed have to be formed variously to afford a difference in heights among such connection lines. This resulted in a problem of increasing a height of the insulator. Further, since the protrusions of various heights have to be formed as shown in FIG. 1 and FIG. 2, a mold to manufacture the insulator becomes complicated and a cost for the insulator increases.
Additionally, even for one phase connection lines, positioning at different heights increases a probability of winding faults and has a problem that a sufficient distance between the connection lines are not secured.
Conventionally, when PCB 60 is positioned at the upper portion of the stator, the starting ends of the stator coils 7′, 8′ and 9′ are directly soldered to the PCB 60, manufacturing process becomes complicated and causes mis-connection.
Therefore, the starting ends of the stator coils 7′, 8′ and 9′ are positioned inside between the stator 1 and the bracket 70 to induce a concern that insulation may not be maintained. Generally, the stator core 2 is pressed and inserted to be fixed inside the bracket 70, and this forms a gap between the inside wall of the bracket and the insulator 4 of the stator very narrow.
Since an insulating tube (unshown) and a structure related to the insulating tube have to be used to fix the neutral point formed by the terminal ends of the stator coils, its manufacturing process is complicated. Further, since such neutral point is fixed on an outside surface of the insulator 4, there is a concern that a fault in insulation between the neutral point and the bracket.